Cluster Computing and the Power of Edge Recognition

We study the robustness--the invariance under definition changes--of the cluster class CL#P [HHKW05]. This class contains each #P function that is computed by a balanced Turing machine whose accepting paths always form a cluster with respect to some length-respecting total order with efficient adjacency checks. The definition of CL#P is heavily influenced by the defining paper's focus on (global) orders. In contrast, we define a cluster class, CLU#P, to capture what seems to us a more natural model of cluster computing. We prove that the naturalness is costless: CL#P = CLU#P. Then we exploit the more natural, flexible features of CLU#P to prove new robustness results for CL#P and to expand what is known about the closure properties of CL#P. The complexity of recognizing edges--of an ordered collection of computation paths or of a cluster of accepting computation paths--is central to this study. Most particularly, our proofs exploit the power of unique discovery of edges--the ability of nondeterministic functions to, in certain settings, discover on exactly one (in some cases, on at most one) computation path a critical piece of information regarding edges of orderings or clusters

Origin of 21+2_1^+ Excitation Energy Dependence on Valence Nucleon Numbers

It has been shown recently that a simple formula in terms of the valence nucleon numbers and the mass number can describe the essential trends of excitation energies of the first $2^+$ states in even-even nuclei. By evaluating the first order energy shift due to the zero-range residual interaction, we find that the factor which reflects the effective particle number participating in the interaction from the Fermi orbit governs the main dependence of the first $2^+$ excitation energy on the valence nucleon numbers.Comment: 9 pages, 5 figure

Direct radiative capture of p-wave neutrons

The neutron direct radiative capture (DRC) process is investigated, highlighting the role of incident p-wave neutrons. A set of calculations is shown for the 12-C(n,gamma) process at incoming neutron energies up to 500 keV, a crucial region for astrophysics. The cross section for neutron capture leading to loosely bound s, p and d orbits of 13-C is well reproduced by the DRC model demonstrating the feasibility of using this reaction channel to study the properties of nuclear wave functions on and outside the nuclear surface. A sensitivity analysis of the results on the neutron-nucleus interaction is performed for incident s- as well as p-waves. It turned out that the DRC cross section for p-wave neutrons is insensitive to this interaction, contrary to the case of incident s-wave neutrons. PACS number(s): 25.40Lw,21.10Gv,23.40.HcComment: 16 pages, REVTeX file, PostScript file, .dvi fil

Effectiveness of slow motion video compared to real time video in improving the accuracy and consistency of subjective gait analysis in dogs

Objective measures of canine gait quality via force plates, pressure mats or kinematic analysis are considered superior to subjective gait assessment (SGA). Despite research demonstrating that SGA does not accurately detect subtle lameness, it remains the most commonly performed diagnostic test for detecting lameness in dogs. This is largely because the financial, temporal and spatial requirements for existing objective gait analysis equipment makes this technology impractical for use in general practice. The utility of slow motion video as a potential tool to augment SGA is currently untested. To evaluate a more accessible way to overcome the limitations of SGA, a slow motion video study was undertaken. Three experienced veterinarians reviewed video footage of 30 dogs, 15 with a diagnosis of primary limb lameness based on history and physical examination, and 15 with no indication of limb lameness based on history and physical examination. Four different videos were made for each dog, demonstrating each dog walking and trotting in real time, and then again walking and trotting in 50% slow motion. For each video, the veterinary raters assessed both the degree of lameness, and which limb(s) they felt represented the source of the lameness. Spearman’s rho, Cramer’s V, and t-tests were performed to determine if slow motion video increased either the accuracy or consistency of raters’ SGA relative to real time video. Raters demonstrated no significant increase in consistency or accuracy in their SGA of slow motion video relative to real time video. Based on these findings, slow motion video does not increase the consistency or accuracy of SGA values. Further research is required to determine if slow motion video will benefit SGA in other ways

Calibration of Computational Models with Categorical Parameters and Correlated Outputs via Bayesian Smoothing Spline ANOVA

It has become commonplace to use complex computer models to predict outcomes in regions where data does not exist. Typically these models need to be calibrated and validated using some experimental data, which often consists of multiple correlated outcomes. In addition, some of the model parameters may be categorical in nature, such as a pointer variable to alternate models (or submodels) for some of the physics of the system. Here we present a general approach for calibration in such situations where an emulator of the computationally demanding models and a discrepancy term from the model to reality are represented within a Bayesian Smoothing Spline (BSS) ANOVA framework. The BSS-ANOVA framework has several advantages over the traditional Gaussian Process, including ease of handling categorical inputs and correlated outputs, and improved computational efficiency. Finally this framework is then applied to the problem that motivated its design; a calibration of a computational fluid dynamics model of a bubbling fluidized which is used as an absorber in a CO2 capture system

Symmetry and Surface Symmetry Energies in Finite Nuclei

A study of properties of the symmetry energy of nuclei is presented based on density functional theory. Calculations for finite nuclei are given so that the study includes isospin dependent surface symmetry considerations as well as isospin independent surface effects. Calculations are done at both zero and non-zero temperature. It is shown that the surface symmetry energy term is the most sensitive to the temperature while the bulk energy term is the least sensitive. It is also shown that the temperature dependence terms are insensitive to the force used and even more insensitive to the existence of neutron skin. Results for a symmetry energy with both volume and surface terms are compared with a symmetry energy with only volume terms along the line of $\beta$ stability. Differences of several MeV are shown over a good fraction of the total mass range in $A$. Also given are calculations for the bulk, surface and Coulomb terms.Comment: 11 pages, 2 figures, Added a new tabl

Abstract Tensor Systems as Monoidal Categories

The primary contribution of this paper is to give a formal, categorical treatment to Penrose's abstract tensor notation, in the context of traced symmetric monoidal categories. To do so, we introduce a typed, sum-free version of an abstract tensor system and demonstrate the construction of its associated category. We then show that the associated category of the free abstract tensor system is in fact the free traced symmetric monoidal category on a monoidal signature. A notable consequence of this result is a simple proof for the soundness and completeness of the diagrammatic language for traced symmetric monoidal categories.Comment: Dedicated to Joachim Lambek on the occasion of his 90th birthda

Flip-chip gate-tunable acoustoelectric effect in graphene

We demonstrate a flip-chip device for performing low-temperature acoustoelectric measurements on exfoliated two-dimensional materials. With this device, we study gate-tunable acoustoelectric transport in an exfoliated monolayer graphene device, measuring the voltage created as high-frequency surface acoustic waves dynamically drive the graphene charge carriers, the density of which we simultaneously control with a silicon back-gate. We demonstrate ambipolar dependence of the acoustoelectric signal, as expected from the sign of the graphene charge carriers. We observe a marked reduction in the magnitude of the acoustoelectric signal over a well-defined range of density in the vicinity of charge neutrality, which we attribute to a spatially heterogeneous charge-disorder landscape not directly revealed by conventional transport measurements.Comment: 7 pages, 5 figure

The Complexity of Computing the Size of an Interval

Given a p-order A over a universe of strings (i.e., a transitive, reflexive, antisymmetric relation such that if (x, y) is an element of A then |x| is polynomially bounded by |y|), an interval size function of A returns, for each string x in the universe, the number of strings in the interval between strings b(x) and t(x) (with respect to A), where b(x) and t(x) are functions that are polynomial-time computable in the length of x. By choosing sets of interval size functions based on feasibility requirements for their underlying p-orders, we obtain new characterizations of complexity classes. We prove that the set of all interval size functions whose underlying p-orders are polynomial-time decidable is exactly #P. We show that the interval size functions for orders with polynomial-time adjacency checks are closely related to the class FPSPACE(poly). Indeed, FPSPACE(poly) is exactly the class of all nonnegative functions that are an interval size function minus a polynomial-time computable function. We study two important functions in relation to interval size functions. The function #DIV maps each natural number n to the number of nontrivial divisors of n. We show that #DIV is an interval size function of a polynomial-time decidable partial p-order with polynomial-time adjacency checks. The function #MONSAT maps each monotone boolean formula F to the number of satisfying assignments of F. We show that #MONSAT is an interval size function of a polynomial-time decidable total p-order with polynomial-time adjacency checks. Finally, we explore the related notion of cluster computation.Comment: This revision fixes a problem in the proof of Theorem 9.

Using on-line video clips to enhance self-efficacy toward dealing with difficult situations among nursing students.

The aim of the study was twofold. The first aim was to develop on-line video clip material that showed examples of nurses dealing with potentially difficult and delicate patient groups. The second aim was to evaluate the effectiveness of video clip materials for enhancing nursing student���s self-efficacy to effectively communicate with the type of patients described above. The production of contextually relevant video clip material involved the identification of relevant material based on real experiences, writing appropriate scripts, recruiting actors, recording the performances and producing them in a form that could be accessed on-line. Self-report questionnaires were used to assess the effectiveness of video clip material. Level 1 (n = 145) nursing students completed a self-efficacy measure that assessed confidence to deal with situations such as breaking news of death, working with children, people with disability and aggressive behaviour at the start and the end of the module. Results indicated that student���s self-efficacy increased noticeably over the course of the module. Differences between increases in self-efficacy attributed to watching videos or attending lectures were marginal. Findings suggest that using video clips that show students effectively coping with adverse situations provide an effective teaching approach for enhancing self-efficacy. Future research is needed to test the extent to which self-efficacy measures relate with nursing performance